The nightmare of knowlege
by thetrueninjagofan12
Summary: Sans knows a lot about Undertale, perhaps too much. What will happen when Sans accidentally reveals himself as more than just a lazy skeleton from Snowdin town? You'll just have to read and see
1. Chapter 1: Genocide

**DISCLAIMER: I do NOT own Undertale. The game, and all corresponding characters, belongs to Toby Fox and Temmie Chang.**

Chapter 1: Genocide

It was the end of the game. This time it was a pacifist run, so they made it to the surface. There was one, though, who wasn't as appealed to this ending as the others. Sans had seen it before, enough times to just expect it to happen, then wait for it to end forever, creating a new timeline. This time was no different. Sans woke up with a start in his bed back in Snowdin. He sighed while getting out of bed.

Sans' P.O.V.

"Here we go again... Let's just hope no one dies. I'm not in the mood to deal with a genocidal maniac."

Oh boy was I wrong. I saw the usual signs of a genocide run. The kid was emotionless and unresponsive to my joke. I also saw dust covering their clothes as they left the ruins. From that moment, I knew that this run was going to end with me dying. I just didn't want it to happen. I tried to save Papyrus. I was just... too... late...

"Damn it Paps, why did you have to believe in everyone so easily..?"

I wasn't even... Upset. I had seen him die enough times to just go completely numb. I was mad, sure, but that feeling won't go away, no matter how many times this happens. So I just teleported to the final corridor, and waited for them to show up and kill me.

"Looks like you've been busy."

I said to them as they walked in. The look on their face was enough to tell me they were successful. I even heard that weed trembling in fear.

"It's a beautiful day outside, Birds are singing, flowers are blooming. On days like this, kids like you, should be burning in hell."

I was impressed that they didn't die to that attack. In any other playthrough, they normally did. So this was new. I was legitimately lost for words for that brief moment.

"... *ahem* Huh. Never understood why people didn't use their strongest attacks first."

They fought hard, that's for sure. It isn't often that I see Frisk win on their first try, so I was surprised when they landed that finishing blow without dying once. I bet 'Player' was really proud of that achievement.

I can always tell when a genocide route is over, because I wake up, as if from a nightmare. It's always the same thing; waking up with a start, hyperventilating, and clutching my shirt, checking to see if the cut is gone. Papyrus usually checks on me, mostly because most of the time I scream when I do so. No matter how many times I die, seeing Papyrus alive again makes me cry of happiness. This time was no different.

No one's P.O.V.

"SANS, ARE YOU ALRIGHT? I HEARD YOU YELL! ARE YOU IN DANGER?"

"N-no bro... just a n-nightmare"

"THANK ASGORE! YOU GOTTA STOP SCARING ME LIKE THAT! WHAT IF YOU HAVING NIGHTMARES, AND ME CHECKING IN ON YOU IN THE DEAD OF NIGHT (...) MAKES ME UNFIT TO CAPTURE A HUMAN?!"

"Priorities, bro... priorities..."

That was when Papyrus realized he was crying.

"OH MY GOD, SANS! WHAT'S WRONG?"

"Huh? Oh. I-it's nothing... I'm fine. You should go back to bed bro. Who knows, a human could come around tomorrow."

"YOU'R E RIGHT! REST WELL BROTHER!"

"Night bro..."

And with that, Sans was left alone to cry.


	2. Chapter 2: The new timeline

Sans was walking to the ruins entrance. He hid behind the trees, waiting for Frisk to leave the ruins. Right on schedule, they walked out. Thankfully, there was no dust that he could see. Maybe this will be a good ending after all.

"Human, don't you know how to greet a new pal? Turn around, and shake my hand."

The whoopee cushion in his hand went off, followed by a little giggle. Sans was relieved. Things were going to be better. Like usual, Sans was following Frisk through the whole game. All the lives they spared, but all the friendships they avoided kind of annoyed him.

"The _hell_ are you doing, kid?"

He asked to himself. Calling Papyrus a loser? Not giving these monsters the time of day? What were they trying to prove by doing this? _Hey, check it out! I survived without killing anybody!_ That's not that big of a thing to prove. Now it was time to judge, but he didn't know what to say. This is something that was rarely done.

"I guess friends are overrated for ya, huh? These monsters just wanted to be friends, but you wouldn't give them the time of day? What are you trying to prove?"

Frisk just stood there, staring at him. They didn't really care WHAT Sans had to say, which annoyed the skeleton deeply.

"Could you at least acknowledge the fact I'm talking to ya? You've been here enough times to know I'm gonna judge you."

He covered his mouth quickly. He wasn't supposed to bring up the fact that he's aware of COMPLETED timelines. He promised GASTER (Gaster) he wouldn't. Frisk just rolled their eyes. They already knew that Sans was aware of timelines. There was definitely something wrong about this timeline though. As soon as Sans covered his mouth the whole world glitched and the game crashed.

It was rebooted, but with a _slight_ problem. Sans was in the judgement hall, with more than Frisk for company. Chara was standing there too, looking VERY confused. They looked at Sans, and jumped at him.

"WHAT THE _HELL_ DID YOU DO, YOU IDIOT?!"

They asked, holding Sans by the shirt.

"YOU'RE LUCKY I'M NOT GONNA KILL YOU RIGHT HERE RIGHT NOW!"

Sans sighed, pushing them off.

"To be honest, I have no idea. Come on; let's see if anything else has changed."

With that, they were gone.

"This is kind of spooky..."

Frisk said wearily. the whole GAME was messed up. As they walked through Hotland, There were Tsunder planes crashing themselves, Vulkins walking into the lava below, and there was a Gaster follower sitting there, as if waiting for them.

"Hello Sans... I'm ashamed of you, betraying Dr. Gaster's word like this. You should know it's rude to go back on your word, especially when they're listening. Look at the consequences of your actions."

Sans felt Chara scowling at him. Frisk stared at the floor, refusing to look at him.

"Gaster did this? Is this punishment for mentioning timelines?"

The Grey monster just laughed, and then vanished.

"Great going, bonehead. Now the entire game is going to hell."

Sans just stared into the empty cavern ahead. Chara was right. It was his fault, and he had to fix it.


	3. Chapter 3: a glitched new world

Waterfall was no better than Hotland. The Temmie village was a horror show. There was a small cluster of Temmies, maybe 5 or 6, merged into one great big deformed mound of Tem. Frisk screamed and hid behind Chara. Sans pulled up a blaster, ready to defend them if he needed to. The Temmie mound paid them no mind; it just moseyed along, ignoring them completely. Gersen's shop was messed up too. He was talking in a weird voice, one Sans recognized as Wing Dings. He placed a sea tea on the counter for them to take, which they didn't. It just looped over and over and over, placing each sea tea on top of each other while the other one just vanished as it was placed down. Aeron and Woshua were merged together, flexing and cleaning everything in sight. Frisk was creeped out. Chara and Sans were ready in case something got hostile. Finally, they made it to Snowdin.

"Why are we wasting our time here, trash bag?"

Sans rolled his eyes. Chara was REALLY getting on his nerves.

"If you will shut up, I'll show you!"

He teleported into his room to get the key to his lab. He wasn't gone for 2 minutes when he heard the kids scream outside. Quickly, he teleported outside.

"Oh, my god."

They were huddled together. Chara had their knife out, ready to defend them both. A very hostile monster was attacking them, one Sans recognized _very_ quickly.

"Papyrus?"

Chara and Frisk stared at the monster. It was Papyrus alright. He was horribly deformed and hostile. Sans quickly wiped the tears off his face and pulled Frisk and Chara away before he could attack them. He brought them to his lab behind his house.

"Wow. You really messed up, huh Sansy boy? I bet you feel _REALLY_ great!"

Chara said with a smug expression. Sans was quickly losing patience.

"I can throw you back if you like."

Chara rolled their eyes.

"Now, are either of you hurt?"

They shook their heads. Sans smiled. Now it was time for them to figure out what happened to the game files to cause this.

"Sans?"

Sans turned to see Frisk. They looked upset.

"Yeah kiddo?"

"I'm scared..."

They hugged him, crying. Sans' expression softened and he hugged the frightened child back.

"I know kiddo, don't worry, I'll do what I can to fix this."

It's been hours. Sans hasn't found much. There have been signs of hacking, but all that proved was why the Gaster follower was there. He was completely stumped.

"Admit it Sans, you broke the game."

"WILL YOU SHUT UP ALREADY, CHARA? There HAS to be a better explanation. It can't be as simple as that. It can't be as simple as making a statement breaking the game."

Frisk and Chara looked at each other. Frisk was the one to speak up now.

"Sans. It's late. Maybe we should rest. Getting sleep may help clear your head."

He shook his head.

"No, Frisk. I can't stop, even for a second. What if I take a break and the world glitches more? I don't understand. Why am **I** the only one who hasn't glitched?"

Chara thought about that statement.

"Maybe it's punishment. After all, YOU caused this. So maybe you haven't glitched so you can live with what you've done, suffering as the only one not affected by this glitch."

Time has passed since then. Sans sighed and stared at the sleeping children. He needed answers, but he also needed to protect these kids regardless of what happens. He can't take them to his house; Papyrus can get to them, if he can even remember who he is or where he lives. He can't go to Undyne, who knows how bad her glitch is, she's hostile regardless. He can't go to Grillby's, fire+glitch=risky. So they were stuck in the small little lab. He picked up a photo of him, Gaster, and Alphys.

"Why, doc? Why is this happening? How can I fix it?"

Then he went to sleep.

It's been hours, Sans was awoken by a loud bang on the door. Chara and Frisk were already awake, Chara with their knife ready, facing the door, and holding Frisk back so they were safe. Sans motioned them to move back and he would investigate. Blaster ready, he opened the door. The face he saw smiling at him was NOT one he expected.

("Greetings, Sans. May I come in?")

Sans beckoned the kids to fall back, but not lower their guard.

"S-sure, doc. Come in..."

Gaster spoke in proper English now, so the kids could understand him.

"I bet you're wondering why I'm here. Though, by the looks of the underground in its current state, I would think it's safe to say you already KNOW why I'm here."

Chara scowled at Sans, who looked like he was about to have a panic attack.

"Do you know how to fix this, Dr? No one else I care about that much, but seeing Papyrus like that, it unsettles and scares me. I ruined my little brother's life. What can I do?"

Gaster looked at Frisk. He felt reset capabilities coming from the child, so he pointed at them.

"Have this child reset. It will erase all changes to the world. You should know this, Sans, I taught you."

Sans shook his head. He knew it wasn't that simple, he wasn't stupid.

"No. I don't think so. The world is glitched, Gaster. It isn't as simple as that."

Gaster sighed and walked over to the machine. There has to be something they can do, but what? They were working for hours trying to figure it out. Chara and Frisk went back to sleep. Regardless of the situation, they were still children.

"Hey, G? Even if the world is glitched, it's good to see you again. Hopefully, with your help we can figure this out. It's nice working together, huh?"

Gaster smiled. It really was nice to be working together again. He just wished his return was for a better reason than being a glitch that was pulled back into the game from the coding. When he woke up in Waterfall, behind the grey door, he was confused. He had no idea how he got back into the game until he saw that everything was glitched. Waterfalls were flowing up, monsters were merged together, poor Undyne was missing half of her body, and Napstablook was affected by gravity, with no arms or legs, and no voice to call out for help. He had figured that Sans knew what was going on, so he came right to Snowdin to see what he knew.

Suddenly, there was a knock on the door. Sans told everyone to stay back. He opened the door and almost blasted Ink's head off.

 **A/N: I don't own Ink. He belongs to someone else. I couldn't find the proper credit. Don't hate me ;^;**


	4. Chapter 4: A whole new perspective

Chapter 4: A whole new perspective

 **A/N: I don't own Ink or Error. They are owned by Crayon Queen and the previously stated unknown credential personnel.**

Ink was bored. He was walking through the multiverse like usual when he saw it happen.

"What in the worlds?"

Undertale just crashed. The page disappeared for a moment, and re appeared a mess. There was a tear on the page, which was now blue. His first thought was Error being behind it, so he went to investigate.

"ERROR!"

The glitch glanced at him, amused. Laughing, he asked him what was up.

"What did you do to Undertale?"

"H-h-ha ha hA HA Ha! Y0u th1nk ! d1d that? 1 W!$H!"

"I'm not messing around Error. What did you do?"

Error was amused by this. Ink was really quick to assume it was him, and he thought it was hilarious.

"M-my Friend, y0u g1vE m3 t00 much CRedIT! Why w0uld ! dE$7r0y Und3r74l3? ! w0uld l0$3 4ll my pupp37s."

"If you didn't do it, then what happened?"

Error shrugged.

"D0n'7 kn0w, d0n'7 c4r3, d0n'7 b07h3r m3."

Ink rolled his eyes at the skeleton and went to investigate.

"This is creepy." He thought to himself.

He walked through the Snowdin forest, or at least he thought it was Snowdin forest. Everything was glitched and deformed. There were upside down trees, snow falling up, monsters walking through solid surfaces. Ink almost screamed when Snowdrake walked through him. ' _I need to get to the bottom of this, fast!'_ He thought to himself. Finally, he made it to town (Which wasn't much better). Ink was just walking when he heard something behind him. Turning around, he was face to face with a very creepy Papyrus. Screaming, he ran for the lab behind Sans' house and pounded on the door. He was greeted by his face almost shot off.

"What the hell, Sans?"

They all stared. What Ink was doing there, they had no idea, but they're kind of glad he showed up.

Hopefully he can be able to tell them what happened to their universe.

"Ink? What the HELL is going on?"

Ink stared at his alternate counterpart. He didn't know either? Sans, of all people, should know what was going on. Now, truly lost for ideas, he decided just decided to ask some questions.

"Okay... can anyone tell me what happened here?"

Shyly, Frisk spoke up.

"Um. We were in the final corridor... and Sans got irritated. I, uh, did a soulless pacifist route, and he accidentally let it slip that he was aware of timelines... then all this happened... If I didn't do the route, we wouldn't be here right now." Then their face shot up with alarm, tears forming in their eyes. "Oh my god! It's my fault!"

Sans quickly started comforting the crying child.

"shhh... no, no it isn't. It isn't your fault. You didn't do anything wrong. Frisk, hey, listen, it isn't your fault, okay?"

Frisk hugged him and sobbed even harder...

"It's my fault... it's my fault... it's my fault..."

Chara put their hand on Frisk's shoulder.

"No it's not kid. It's Sans'. He's the one who got us in this mess."

If looks could kill, Chara would be a bloody pile of goo. Sans looked ready to strangle the kid at that very moment. Ink felt bad to be entertained by the dispute. But he had to keep going on the interrogation.

"Have there been any signs of this happening before? Maybe hints of hacking being done to the game? Anything at all?"

Sans' head shot up at once. Hacking! Why hadn't he thought of that? He ran to the computer and started working. And Ink was right. There have been signs of the game being hacked. It was obviously amateur work though, because everything was all out of whack.

"Yep, we are definitely dealing with a hacker here. But look at this! They clearly didn't know what they were doing! Binomials are jumbled left and right, some spots have random 1s or 0s thrown in! Honestly people, if you don't know what you're doing, don't do it!"

Frisk, Gaster, and Ink walked over as well.

"Is there any way to fix this, Sans? Ink? Dr?"

"Someone will probably have to go and do it manually, unless this computer will do it here." Ink sighed. "Though it might be dangerous to do so, no one has survived being dragged into the files."

Gaster coughed. Sans looked at the monitor awkwardly. Ink got the impression he was wrong.

("I have. In fact the reason I'm here is due to the fact that the glitch dragged me out of the game files into the game. Perhaps I can be the one who goes to fix the coding.")

"NO! I just got you back! I can't lose you now! There HAS to be another way!"

("Sans. Please. If losing my physical form will fix the game, I'll do it. Don't you want-")

He was cut off by a small sob coming from behind. They turned around to see Frisk sobbing with their face buried into their knees.

"WOAH! Hey, kiddo. What's wrong?"

"I'm sorry Sans...I'm so sorry..."

"For what? You didn't do anythi-"

"FOR NOT **WANTING** THE TIMELINE FIXED, OKAY?! I DON'T **WANT** IT FIXED!"

"What? Frisk, I-"

"NO! I CAN'T DO IT! NOT ANYMORE!"

"Frisk! What are you talking about?"


	5. Chapter 5: Bring it in guys!

**A/N: Still don't own anything guys!**

Everyone was surrounding the distressed child. _'I don't want it fixed'_? But why? What happened to Frisk to put this on?

"I'm just so SICK of being a puppet, y'know? Being separated from Chara makes me feel free, makes me feel like I have control over my OWN life. Even before my genocide route I felt like I didn't have control over my actions. I couldn't even TALK! I couldn't express emotions. As soon as I fell underground, I lost all self control. That all went into the player's hands. I just- I just- I WISH I NEVER FELL DOWN TO BEGIN WITH!"

Sans stared at them shocked. Ink seemed intrigued, having never seen any Frisk express so much emotion at all (Was this what they meant?) Sans' shock broke and they comforted the sobbing child.

"Shhh... it's alright. I know you don't mean it kiddo. Don't even try to convince yourself otherwise, you'll just work yourself up again."

"I'm just so sick of being a 'thing' to people. I'm just an image of pixels that moves on a screen. They don't care what they do, or what it does to ME. They just think I'm the silent protagonist in a video game. They don't care about how I feel, or if I actually have emotions. They play for their own benefits, not mine. That's why I haven't been given a route where everyone is happy, because they feel _adventurous_ and want to explore the different routes. I honestly don't want to go through any of that again. "

Ink sat down beside them as well.

"I understand, Frisk. But the game can't stay this way. The entire multiverse could collapse if we don't fix it. I saw the game as it crashed. When it reloaded, it was blue, indicating an error. But the other thing I saw was that it was TORN. If we don't fix this game soon, then it will become irreparable, and be completely destroyed. This will slowly destroy all surrounding and corresponding Aus. Do you really want that?"

Frisk sighed and shook their head.

"So you will cooperate?"

Frisk nodded.

"Good. So how are we doing this? Send in the doctor? Or try to find another way?"

"I vote another way!"

("I volunteer to go in and fix it manually. Fixing the game will send me there anyways, so there isn't a point to avoid doing so.")

Sans hugged the other skeleton. And spoke to him in his font.

("I love you dad.")

("I love you too, my son. Goodbye.")

With that he went to the machine under the cloth, and got pulled into the files. Within minutes, the game was fixed, with Sans and Frisk right back where they started, at the end of the game.

"Huh. I guess he did it. I hope that doesn't happen again, right kid?"

Frisk said nothing. Sans sighed, remembering that Frisk can't speak normally.

"I won't hold things off for you any longer kiddo. Go on ahead-"

Frisk hugged the skeleton, and whispered 'Thank you'. Sans' expression softened.

"You're welcome, bucko. Best get a move on. Asgore's waiting for ya."

With that, Frisk walked away.

Ink left Undertale, feeling very happy with the work he's done. Though he didn't directly fix the game, he still helped. And made sure Frisk didn't lose full control. At this time, they might be at Asgore.

"Thanks for changing my life guys. I'll come and visit again some time."

"W-w3lc0m3 b4ck !nk!"

"Thanks for the help, not so much."

"D1dn't th1nk y0u n3Ed3d it. YEt 4g41n, ! d1dn't r34lly c4r3."

"Whatever. I've seen enough hell to NOT need to deal with you. So see ya."

Error laughed. He'll be back, he usually is. Besides, he'll need to come back. Error left him a little surprise with Underswap.

The end


End file.
